Strapping machine

ABSTRACT

1. APPARATUS FOR SECURING A TENSIONED PLASTIC STRAP ABOUT AN ARTICLE, SAID APPARATUS COMPRISING MEANS FOR SUPPORTING AN ARTICLE IN STRAPPING POSITION, GRIPPING MEANS FOR HOLDING THE LEADING END OF A STRAP LOOPED ABOUT THE ARTICLE IN RELAXED SPACED OVERLAPPING RELATIONSHIP WITH RESPECT TO A STRAP PORTION EXTENDING TO A SUPPLY, TENSIONING MEANS FOR TENSIONING THE STRAP ABOUT THE ARTICLE, HOLDING MEANS FOR HOLDING THE STRAP UNDER TENSION ABOUT THE ARTCLE, MEANS FOR DISENGAGING SAID TENSIONING MEANS WHEREBY THE   STRAP PORTION EXTENDING TO THE SUPPLY FROM SAID HOLDING MEANS IS RELAXED, MEANS FOR MELTING THE FACING SURFACE AREAS OF THE OVERLAPPING STRAP PORTIONS SQUEEZING MEANS FOR SQUEEZING THE MELTED SURFACE AREAS TOGETHER WHEREBY A FUSED JOINT IS FORMED, AND CUTTING MEANS FOR CUTTING THE STRAP FROM THE SUPPLY ADJACENT THE FUSED JOINT.

Aug. 28, 1973 R. J. BILLETT ET AL Re. 27,744

STRAPPING MACHINE Original Filed Dec. 29, 1964 4 Sheets-Sheet 1 W F I V/7///////////////////// Aug. 28, 1973 R. J. BILLETT ETAL Re. 27,744

STRAPPING MACHINE 4 Sheets-Sheet 2 Original Filed Dec.

Aug. 28, 1973 Original Filed Dec. 29. 1964 R. J. BILLETT ETAL STRAPPINGMACHINE 4 Sheets-Sheet 5 STRAPPING MACHINE 4 Sheets-Sheet 4 OriginalFiled Dec. 29, 1964 United States Patent Matter enclosed in heavybrackets If] appears in the original patent but forms no part of thisreissue specification; matter printed in italics indicates the additionsmade by reissue.

15 Claims This invention relates to a machine for binding bundies,boxes, packages and the like with a tensioned loop of plastic strappingand more particularly to a machine which secures the overlapping ends ofthe strapping with a tension resisting heat seal.

As a substitute for the well-known steel band strapping, there haverecently been developed high strength strapping materials formed of suchlong chain linear polymers or plastics as polypropylene and nylon. Suchstrapping material is made by extruding the molten polymer through anorifice and then either stretching or cold rolling the extruded productto orient the molecules longitudinally thereof with resultant greatlyincreased tenacity and tensile strength. In securing overlapping ends ofplastic strapping by means of a heat seal, special techniques arerequired in order to avoid disorientation of the molecules andconsequent loss of strength. Strapping of this nature also requires, atleast for fully satisfactory results, special apparatus for feeding,tensioning, cutting and other handling operations. This type ofstrapping will be referred to herein as plastic strapping and it istoward a machine for handling such strapping that the present inventionis directed.

It is the over-all object of the present invention to provide anautomatic machine for lacing a length of plastic strapping about anobject, tensioning the strapping, securing overlapping strap portionstogether by means of a heat seal and cutting the secured strap from thesupply at a point closely adjacent the heat seal.

A further object of the invention is to provide improved apparatus forheat sealing overlapping ends of tensioned plastic strapping in a mannerto obtain a joint having a high degree of efiiciency.

Other and further objects, features and adavntages of the invention aswell as mechanisms ancillary thereto and subcombinations thereof will beexplained or will become apparent as the description of the preferredembodiment proceeds.

Referring now to the drawing:

FIG. 1 is a vertical section through the machine;

FIG. 2 is a diagramamtic side elevational view of the machine;

FIG. 3 is a section taken along the line IIIIII of FIG. 2;

FIG. 4 is a section taken along the line IV-IV of FIG. 2;

FIG. 5 is a section taken along the line VV of FIG. 2;

FIG. 6 is a fragmentary view showing the location of one of the switchesused to control the machine;

FIG. 7 is a vertical section showing a portion of the operatingmechanism of the sealing unit;

FIG. 8 is a sectional view showing a portion of the strap gripping andcutting mechanism;

FIG. 9 is a fragmentary sectional view showing the drive for the camsthat operate the members shown in FIG. 8;

Re. 27,744 Reissued Aug. 28, 1973 FIG. 10 is a section taken along theline X-X of FIG. 1;

FIG. 11 is a side elevational view of a switch and switch operatinglever;

FIG. 12 is a fragmentary elevational view showing a cam that operatesthe strap gripping members;

FIG. 13 is a fragmentary elevational view showing a cam for operating astrap cutting and seal squeezing member; and

FIG. 14 is a schematic wiring diagram.

Referring first of FIG. 2, the machine comprises a base section 10containing the various operating mechanisms. The top of base 10 forms atable 12 on which a package 14 to be strapped may be rested within theconfines of a yoke 16 extending upwardly from the base section. A roll18 of plastic strapping is suitably mounted alongside the machine andthe strapping 20 from the roll is directed about guides 22 to a pointnear the right hand lower corner of yoke 16 where it is engaged with afeeding and tensioning mechanism as will presently be explained for pushfeeding the strap through the yoke.

As shown in section in FIGS. 3, 4 and 5, yoke 16 is formed of a channelmember or members having an open side facing inwardly of the loop formedby the yoke. Along the straight arms of the yoke, that is the twovertical sides and the horizontal top, track forming spacers 24, one ofwhich is shown in FIGS. 4 and 5, are secured by means of screws 26 toone of the inner faces of the channel members. Extending through spacers24 and the adjacent side of the channel member are a plurality of bolts28 surrounding which are springs 30 which hold an angle member 32resiliently against one face of the spacer as shown in FIG. 5. One edgeof angle member 32 is curved to fit into a groove 34 extending along thewide face of spacer 24 and an arm 36 of the angle member is spaced fromthe narrow face of the spacer so as to slidably and guidingly confinestrap 20 to the contour of yoke 16 as the strap is push-fed therearound.As will presently be explained, the strap is fed around the yoke so asto form a strap loop prior to the placement of the package in strappingposition and the arms 36 of the angle members not only serve to guidethe strap but to support it against the yoke until such time as the loopis drawn tight about the package. During the actual strapping operation,as the strap is tensioned it presses outwardly against the arms 36 andsprings 30 yield to permit the angle members to pivot about therespective grooves 34 whereby the arms 36 release the strap and permitit to escape from the yoke and be drawn down against the package. It isnot necessary to confine the strap at the corners of the yoke and in thecorners, curved guide tracks, one of which is indicated at 38 in FIG. 3,are provided. A guide plate 40 is secured to track 38 but this platedoes not overlie the face of the strap as do the angle members 32.

Referring now to FIG. 1; from the last of the guide rollers 22 strap 20passes through a slot 42, part way about a roller 44, thence about themajor portion of the periphery of a feed wheel 46 having a smooth orslightly roughened surface, part way about a roller 48 and into a guideslot 50 leading toward the table 12. Wheel 46 is secured to a shaft 52to which is also secured a pulley or sprocket wheel 54 connected througha drive belt or roller chain 56 to a reversible air motor 58, wherebywheel 46 may be rotated in opposite directions.

Rollers 44 and 48 are mounted for free rotation on shafts 60 and 61respectively which are secured between a pair of hell crank levers 62,only one of which is shown. Shaft 60 extends through an elongated slot63 in a stationarily mounted block 65 and shaft 61 extends through anelongated slot 67 in said block, the slots 63 and 67 being oppositelysloped as indicated in FIG. 1. The bell crank levers and the rollers 44and 48 are thus fioatingly mounted to a limited degree. Downwardlyextending operating arms of bell crank levers 62 are connected to thepiston 64 of a double acting air cylinder 66.

When strap is to be fed around yoke 16, air motor 58 is driven in thedirection to cause the wheel 46 to turn clockwise, as viewed in FIG. 1,and simultaneously, air is admitted to cylinder 66 so as to rock bellcrank levers 62 counterclockwise to thereby pinch the strap betweenwheel 46 and roller 48. Since the strap is wrapped about a considerablepart of wheel 46 before being pinched by roller 48, a large area ofcontact is assured between driving wheel 46 and the strap so thatlocalized friction which could damage the strap is avoided. Localizedfriction could be particularly harmful to molecularly oriented plasticstrapping inasmuch as the heat produced thereby could result in loss ofmolecular orientation of the strap. When the strap is to be tightenedabout the package, air motor 58 is driven in the direction to rotatewheel 46 counterclockwise and simultaneously, double acting air cylinder66 is operated so as to rock bell crank levers 62 clockwise to cause thestrap to be pinched between Wheel 46 and roller 44. It is during thetightening or tensioning of the strap that the large area of contactbetween the strap and the surface of wheel 46 is particularly importantinasmuch as it is during tensioning that the strap offers the greatestresistance to movement and consequently the greatest opportunity tooverheating.

From guide slot 50 the end of the strap passes through a slot 68provided in a strap gripping member 70 which is pivotally mounted at 72.From slot 68 the strap proceeds between a heavy cantilever section 74 oftable 12 and a strap gripping end 76 of a member 78 which is pivotallymounted at 80 on the machine framework and thence into a groove 82 (seealso FIG. which is cut into the surface of table 12 and which is coveredby a retractable member 84 whereby the strap is properly guided into thelower left hand corner of the yoke 16. As the strap end leaves the lowerright hand end of the yoke it passes between a plate 85 (see alsoFIG. 1) ex tending part way across an open slot in the top of table 12and a gripping portion 86 of the pivotally mounted member 70 and finallyengages the upper end of a switch operating lever 88.

As shown in FIG. 11, lever 88 is pivotally mounted at 99 and has an arm92 overlying an operating member 94 of a switch 96. As will presently beexplained, when the end of the strap engages lever 88 so as to rock saidlever counterclockwise shown in the drawings, switch 96 is elfective toopen an electric circuit to a solenoid valve which stops air motor 58whereby feeding of the strap is discontinued.

With the strap thus formed into a loop extending across table 12 andthrough the yoke 16, the machine is conditioned for performing thestrapping operation and after the package is positioned on the table, anair motor 100 is started. Motor 100 is connected through a speedreduction unit 101 and a roller chain 102 to a sprocket 104 secured to amain drive shaft 106 for controlling the various functions of themachine.

Drive shaft 106 is rotated in counterclockwise direction as viewed inFIGS. 1, 12 and 13 and secured to said shaft is a cam 108 having asegment 110 of reduced diameter. When the machine is at rest, camfollower rollers 112 and 114 lie against the low segment of the cam.Roller 112 is mounted on the free end of an arm 116 pivotally mounted onthe framework at 120 and articulated through a connection comprising acompression spring 122 to member 70. A spring 124 (see FIGS. 7 and 8)extending between a pin 126 on arm 116 and a fixed anchor pin 128 urgesthe free end of arm 116 downward so as to hold the roller 112 in contactwith the surface of earn 108. As shaft 106 starts to turn, roller 112almost immediately moves onto the high portion of the cam therebyrocking arm 116 so as to compress spring 122 and through said springswing member 70 upward to pinch or grip the strap between plate andportion 86 of member 70. This effectively anchors the free end of thestrap.

A cam 130 (see FIG. 7) is secured to shaft 106 and right after the shafthas turned sufiiciently to cause the strap to be gripped between plate85 and portion 86 of member 70 as aforesaid, cam 130 operates the switch132 of a solenoid operated valve 136 (see FIG. 14) to start air motor 58to turn in the direction to retract the strap and tension the same aboutthe package. Valve 133 also admits air to one end of a cylinder 134 (seeFIG. 10) so as to cause the piston 136 of said cylinder to rotate a gearsegment 138 in clockwise direction. Gear segment 138 is meshed with arack 140 cut into the retractable strap track cover 84 and thus as thetensioning of the strap begins, cover 84 is slid away from the strap sothat it may move up into contact with the bottom of the package. Thereis a manually operated pressure regulating valve in the line leading tomotor 58 and when the torque of the motor reaches the value provided bythe preselected pressure, the motor stalls, thus determining the amountof tension applied to the strap. The amount of tension will normally beregulated in accordance with the type of package. Thus for a softpackage, a light tension will usually be called for whereas highertensions will be used when strapping firm or hard objects.

When the article being strapped is small it of course takes more time toshrink the strap loop into conformity therewith than when the articlemore nearly conforms to the size of yoke 16. To assure suflicient straptensioning time to handle small articles, motor 100 is stopped at thetime motor 58 is started and motor 100 is not restarted until near theend of the tensioning operation. This will be more fully explainedlater, but brietfiy the action is accomplished by means of a cam 142 onshaft 106 (see FIGS. 7 and 14) which causes a switch 144 to open acircuit to a solenoid operated valve 146 in the line leading to motor100 at the same time that cam 130 is closing switch 132 to start motor58 as aforesaid. A switch 148 (see FIGS. 1 and 6 and 14), in conjunctionwith switch 144, re-establishes a circuit to solenoid valve 146 as thestrap is pulled out of the lower right hand corner of the yoke. Sincethe strap end is held near this corner of the yoke, tension applied bywheel 46 is transmitted last to the part of the strap in the vicinity ofswitch 148 so that the tensioning operation is nearly completed whenmotor 100 1s restarted.

As motor 100, drive shaft 106 and cam 108 again begin to turn, camfollower 114 rides onto the high part of said cam. Roller 114 is carriedon the free end of a lever 150 pivotally mounted on a rod 152 andarticulated through a compression spring 154 to the pivotally mountedrnember 78. A spring 156 (see FIGS. 7 and 8) extendmg between a pin 158in lever 150 and a fixed pin 160 holds roller 114 against the peripheryof cam 108 at all times. As roller 114 moves onto the high part of saidcam, the resultant motion of lever 150 is transmitted through spring 154to member 78, thereby swinging said member about its pivot and causingthe end 76 thereof to pinch the strap against the heavy section 74 oftable 12.

Between switch operating lever 88 and the point where the strap isgripped between plate 85 and gripping portion 86 of member 70,overlapping but spaced apart strap portions are provided, the endportion of the strap being held away from the underlying portion adistance equal to the space between the gripping surface of grippingportion 86 and the slot 68 (see FIG. 1).

Swingably mounted on a pin 162 secured to the framework is a lever 164(see particularly FIGS. 1 and 7) carrying a cam following roller 166. Aspring 168 extending between a pin 170 secured in lever 164 and a fixedanchor 172 urges said lever in the direction to maintain roller 166 incontact with a face cam 174 which is secured to or formed integrallywith the heretofore re ferred to cam 108. For the most part roller 166rides a high surface of cam 174 but immediately after cam 108 actuatesthe lever 150 a low surface of cam 174 is presented to the roller andspring 168 thereupon becomes effective to rock lever 164 from the dottedline position shown in FIG. 7 to the full line position. At its upperend lever 164 has secured thereto and insulated therefrom a resistanceheating element 176 including a thin bladelike portion 178. Wires 180partially shown in FIG. 7 supply an electric current to the heatingelement which is maintained hot at all times the machine is in use. Whenlever 164 is rocked as aforesaid, blade 178 enters into the spacebetween the overlapping strap portions between lever 88 and grippingmember 86.

As best shown in FIG. 9, a cam 182 is mounted on a hub 184 of cam member108 and the two cams are secured together for unitary rotation by meansof screws 186 or otherwise. As indicated in FIG. 13, a cam followerroller 188 rides the surface of cam 182. Roller 188 is carried on thefree end of an arm 190' which is pivotally mounted on the rod 152. Aspring 192 extending between a pin 194 secured in arm 190 and a fixedanchor pin 196 (see FIG. 7) urges the arm downward to keep the followerroller 188 in contact with the surface of cam 182. Arm 190 is connectedthrough a compression spring, not shown but similar to spring 154, to alever 198. Lever 198 is pivotally mounted on the same pivot 80 whichcarries member 78. As shown in FIG. 1, lever 198 is longer than member78 and is provided with a head portion 200 which extends in front ofmember 78 in alignment with the overlapping portions of the strap.

As soon as the heated blade 178 enters between the overlapping strapportions as aforesaid, a high surface 202 of cam 182 is presented tofollower 188 and the follower moves from a low or radially inwardsurface 204 of the cam onto the high surface thereof. This results inrocking lever 190 upward and consequently in rocking lever 198 to causethe head portion 200 thereof to squeeze the overlapping strap portionsagainst the hot blade 178. An edge of head portion 200 and the edgebetween gripper 86 and slot 68 co-operate to cut the strap at that pointas head portion 200 moves to strip squeezing position. At a point intime between the gripping of the strap by members 74 and 76 and theoperation of levers 198, cam 130 becomes effective to stop motor 58 sothat there is no tension on the strap at the time it is cut. This isimportant because unless motor 58 were stopped, the tensioning wheel 46would completely unlace the strap after it was cut. It is also importantthat the strap not be under tension at the place of the cut because thehighly molecularly oriented strap will split longitudinally when it isout while under tension and such splitting would interfere with thesubsequent feeding of the strap through the yoke.

The low portion of face cam 174 encompasses only a very small arc andconsequently very shortly after the overlapping strip portions aresqueezed against hot blade 178, cam 174 is effective to swing lever 164back to the dotted line position shown in FIG. 7 and thus remove the hotblade so that head portion 200 may move the heated strap portions intodirect engagement. When the plastic strap is made of polypropyleneresin, blade 178 is maintained at a temperature of about 750 F. and isallowed to remain between the strap portions for only a fraction of asecond. This is suflicient to soften or melt the faces of the strap sothat the strap portions fuse together upon contact. It is essential thatonly the surface areas of the strap be melted for otherwise the entirecross section of the strap will become molecularly unoriented and thefused joint will be deficient in tensile strength. By melting the strapportions to a depth of only a minor part of the cross section moleculardisorientation of the major part of the cross section is avoided and thejoint thus produced has 80% or more of the strength of the strap itself.Other types of plastic straps may be heat sealed in a similar manner butthe blade temperature and to a lesser extent the time that the blade isallowed to remain between the overlapping strap portions need to bevaried in accordance with the particular plastic.

After blade 178 is removed, shaft 106 continues to turn and cam 108continues to cause the strap to be gripped between members and 86 andbetween members 74 and 76. This condition is maintained until near theend of the cycle when cam follower rollers 112 and 114 drop onto the lowsegment 110 of the cam. Cam 182 also continues to cause the overlappingstrap portions to be squeezed together by the head 200 of lever 198until near the end of the cycle when follower 188 returns to the lowsegment 204 of the cam. The cycle is long enough so that the squeezingforce of head 200 is maintained until the heated strap portions havecooled but this only requires about two seconds since the strap has beenmelted to only a very shallow depth. By maintaining the grip on thestrap at 74, 76 and 85, 86 no tension is applied to the strap jointuntil it has been cooled. The tension in that section of the strapbetween wheel 46 and the point where it is gripped between members 74and 76 is of course removed when the strap is cut as aforesaid.

Right after cams 108 and 182 have permitted release of the strap, a highpoint 206 of cam 142 (see FIG. 14) operates switch 144 in a manner tobreak the circuit to the solenoid valve controlling air motor and saidmotor thereupon stops. The package is then removed by sliding the strapsideways from beneath plate 85 and the heavy section 74 of the table 12.The act of removing the strapped package relieves the pressure on switchoperating lever 88 and as will presently be explained this causes themotor 58 to be started in strap feeding direction whereby strap is againfed through the yoke to condition the machine for the next strappingoperation.

Referring now particularly to FIG. 14, the machine is preliminarilyconditioned for operation by closing the contact blades 208 and 210 of atoggle switch whereby a circuit is established from power line 212through leads 214 and 216 to the input of a transformer 218 the outputof which is connected to the heating element 176. The contact blades 220and 222 of a second toggle switch are then closed and the machine isthen fully conditioned. If at this time the strap is not threadedthrough the yoke 16 so that the strap end is hearing against lever 88,switch 96 is making contact between a line 224 and a line 226. Line 226leads to a solenoid operated valve 228 which when energized causes strapfeeding and tensioning motor 58 to run in the strap feeding directionand also admits air to cylinder 134 so as to move strap track cover 84to the position shown in FIG. 10. Solenoid valve 228 is connectedthrough leads 230 and 232 back to the power line and thus when switch 96connects lines 224 and 226 strap is fed through the yoke as previouslydescribed until the end of the strap strikes switch operating lever 88.Lever 88 then operates switch 96 to break the connection between lines224 and 226 and establish a connection between line 224 and a line 234.

When the strap is within the yoke it bears against an operating member235 (see FIG. 6) of switch 148 and causes said switch to establish aconnection between line 234 and a line 236 leading to one side of a pushbutton starter switch 238. The other side of switch 238 is connected tothe power line through a line 240 containing a relay 242 having a set ofcontacts 244 arranged to maintain the circuit between lines 236 and 240after push button switch 238 is released by the operator. Line 240 isconnected through a line 246 to one of the contacts of the switch 144another of the contacts of which is connected through a line 248 to thesolenoid valve 146 controlling main drive motor 100. Solenoid valve 146is also connected to the power line through a lead 250 and the line 232.When the machine is at rest, cam 142 holds 7 switch 144 in the conditionindicated in FIG. 14 so as to form a connection between lines 246 and248.

After positioning the package within the confines of the yoke, the pushbutton starter switch 238 is closed thus establishing a circuit to thesolenoid valve 146 of the main drive motor 100 through lines 224, 234,236, 240, 246, 248, 250 and 232. Motor 100 then begins to drive the maindrive shaft 106 carrying the various control cams as hereinbeforedescribed. When cam 130 reaches the rotated position wherein it operatesswitch 132, said switch is caused to close a circuit between a line 252connected to line 234 and a line 254 leading to the solenoid valve 133which when energized causes motor 58 to operate in strap tensioningdirection and also causes strap track cover 84 to be withdrawn. Solenoidvalve 133 is connected to the power line through a line 256 and the line232 so that said valve is energized when switch 132 closes the circuitbetween lines 252 and 254.

At the moment that earn 130 effects the starting of motor 58 orimmediately thereafter, the high surface 206 of cam 142 passes beyondthe operating member of switch 144 and the switch then breaks theconnection between lines 246 and 248 and establishes a connectionbetween line 248 and a line 258. With the switch 144 open between lines246 and 248, solenoid valve 146 is de-energized and main drive motor 100stops. Motor 58 however continues to operate to effect the tightening ofthe strap about the package.

As previously mentioned, the last part of the strap to be pulled out ofthe yoke is that portion in the vicinity of the operating arm 235 ofswitch 148. When this happens, switch 148 breaks the connection betweenlines 234 and 236 and establishes a connection between lines 234 and238. This action of switch 148 energizes the solenoid 146 through lines224, 234, 258, 248, 250 and 232. The breaking of the connection betweenlines 234 and 236 also de-energized relay 242 and opens the circuitbetween lines 236 and 240. Motor 100 then again begins to drive shaft106 carrying the various operating cams with the previously explainedresults. At the end of the cycle, the high surface 206 of cam 142repositions switch 144 to the condition shown in the diagram, thusde-energizing solenoid valve 146 and stopping motor 100.

When the strapped package is removed, switch 96 establishes the circuitto solenoid valve 228 thus feeding strap through the yoke as aforesaidand the machine is then conditioned for the next strapping operation.

The greater part of the apparatus may be used without the yoke 16 andthis may be particularly desirable when strapping packages of such largesize that the provision of a yoke is impractical. Without the yoke, themachine becomes less automatic and in this event solenoid valve 228 isremoved from the circuit and provision is made for the operator tomanually control the feeding of the strap. However, after manuallycausing the desired amount of strap to be fed, the operator inserts theend of the strap into the space between plate 85 and strap gripper 86and shoves the end against switch operating lever 88 to therebycondition the machine for performing the various other functions uponsubsequent operation of starter switch 238.

Having thus described a preferred embodiment of the invention, what isclaimed is:

1. Apparatus for securing a tensioned plastic strap about an article,said apparatus comprising means for supporting an article in strappingposition, gripping means for holding the leading end of a strap loopedabout the article in relaxed spaced overlapping relationship withrespect to a strap portion extending to a supply, tensioning means fortensioning the strap about the article, holding means for holding thestrap under tension about the article, means for disengaging saidtensioning means whereby the strap portion extending to the supply fromsaid holding means is relaxed, means for melting the facing surfaceareas of the overlapping strap portions, squeezing means for squeezingthe melted surface areas together whereby a fused joint is formed, andcutting means for cutting the strap from the supply adjacent the fusedjoint.

2. [The apparatus set forth in claim 1] Apparatus for securing atensioned plastic strap about an article, said apparatus comprisingmeans for supporting an article in strapping position, gripping meansfor holding the leading end of a strap looped about the article inrelaxed spaced overlapping relationship with respect to a strap portionextending to a supply, tensioning means for tensioning the strap aboutthe article, holding means for holding the strap under tension about thearticle, means for melting the facing surface areas of the overlappingstrap portions, squeezing means for squeezing the melted surface areastogether whereby a fused joint is formed, and cutting means for cuttingthe strap from the supply adjacent the fused joint, wherein said cuttingmeans comprises cooperating edges on said gripping means and saidsqueezing means.

3. Apparatus for securing a tensioned plastic strap about an article,said apparatus comprising means for supporting an article in strappingposition, gripping means for holding the leading end of a strap loopedabout the article in relaxed spaced overlapping relationship withrespect to a strap portion extending to a supply, tensioning means fortensioning the strap about the article, holding means for holding thestrap under tension about the article, said holding means being locatedso that the overlapping strap portions are between said holding meansand said tensioning means, means for disengaging said tensioning meanswhereby the strap is relaxed between said holding means and saidtensioning means, means for melting the facing surface areas of theOverlapping strap portions, squeezing means for squeezing the meltedsurface areas together whereby a fused joint is formed, and cuttingmeans for cutting the strap from the supply adjacent the fused joint.

4. The apparatus set forth in claim 3 wherein said cutting meanscomprises cooperating edges on said gripping means and said squeezemeans.

5. The apparatus set forth in claim 3 comprising strap feeding means,and means for guiding the leading end of the strap from said feedingmeans to said gripping means.

6. Apparatus for securing a tensioned plastic strap about an article,said apparatus comprising means for supporting an article in strappingposition, gripping means for holding the leading end of a strap loopedabout the article in relaxed spaced overlapping relationship withrespect to a strap portion extending to a supply, tensioning means fortensioning the strap about the article, holding means for holding thestrap under tension about the article, a heating element, means forinserting said heating element into the space between the overlappingstrap portions, squeezing means for squeezing the overlapping strapportions against said heating element to effect a melting of thesurfaces of the strap in contact with the heating element, and means forwithdrawing said heating element from between said overlapping strapportions to permit said squeezing means to force the melted surfaces ofthe strap together whereby a fused joint is formed.

7. Apparatus for securing a tensioned plastic strap about an article,said apparatus comprising means for supporting an article in strappingposition, gripping means for holding the leading end of a strap loopedabout the article in relaxed spaced overlapping relationship withrespect to a strap portion extending to a supply, tensioning means fortensioning the strap about the article, holding means for holding thestrap under tension about the article, said holding means being locatedso that the overlapping strap portions are between said holding meansand said tensioning means, means for disengaging said tensioning meanswhereby the strap is relaxed between said holding means and saidtensioning means, a heating element, means for inserting said heatingelement into the space between the overlapping strap portions, squeezingmeans for squeezing the overlapping strap portions against said heatingelement to effect a melting of the surfaces of the strap in contact withthe heating element, means for withdrawing said heating element frombetween said overlapping strap portions to permit said squeezing meansto force the melted surfaces of the strap together whereby a fused jointis formed, and means for cutting the strap from the supply adjacent saidfused joint.

8. The apparatus set forth in claim 7 wherein the means for cutting thestrap comprises cooperating edges on said squeezing means and saidgripping means.

9. In a strapping machine wherein a plastic strap is formed into a loopwith the free end thereof overlapping and spaced from a portion of thestrap extending to a supply, a main drive shaft, a main motor fordriving said shaft, strap tensioning apparatus, an air motor for drivingsiad tensioning apparatus, means for starting said main motor, strapgripping means for holding the free end of the strap stationary, meanson said drive shaft for operating said strap gripping means, means onsaid drive shaft for starting said air motor to effect a tensioning ofthe strap, means for stopping said main motor when said air motor isstarted, means for restarting said main motor prior to the completion ofthe tensioning operation, a heating element having a home position,means for mov ing said heating element from its home position to aposition between the overlapping strap portions, squeezing means, meanson said main drive shaft for causing said squeezing means to squeeze theoverlapping strap portions against said heating element to effect asoftening of the face areas of the strap in contact with the heatingelement, means for restoring said heating element to home positionwhereby said squeezing means may squeeze the softened faces of the straptogether to effect a fused joint, means for cutting the strap from thesupply adjacent the joint, and means operable by said main drive shaftfor stopping said main motor.

10. The apparatus set forth in claim 9 comprising holding means forholding the strap under tension, said holding means being so locatedthat the overlapping strap portions are between said holding means andsaid tensioning apparatus, means on said main drive shaft for operatingsaid holding means prior to operation of said heating element, and meansfor stopping said air motor after operation of said holding meanswhereby the strap is relaxed between said holding means and saidtensioning apparatus.

11. In a strapping machine wherein a plastic strap is formed into a loopwith the free end thereof overlapping and spaced from a portion of thestrap extending to a supply, a support for supporting an article withinthe confines of the strap loop, gripping means for holding the free endof the strap stationary, tensioning means for tensioning the strap loopabout the article, said tensioning means comprising a wheel about amajor portion of the periphery of which the strap passes and an airmotor for driving said wheel, means for admitting air to said motor tocause the tensioning of the strap, holding means for holding the strapunder tension, said holding means being located so that the overlappingstrap portions are between the holding means and said wheel, means forstopping the flow of air to said motor whereby the tension in the strapis relaxed between said holding means and said wheel, a heating elementmovable from a home position to a position between the overlapping strapportions, squeezing means for squeezing the overlapping strap portionsagainst said heating element to cause the faces of the strap in contactwith said heating element to soften, means for moving said heatingelement back to home position to permit said squeezing means to squeezethe softened faces of the strap together to effect a fused joint, saidsqueezing means and said gripping means having cooperating edgeseffective to cut the strap therebetween when said squeezing means isoperated.

12. Apparatus for securing a tensioned strap about an article, saidapparatus comprising a support for supporting an article in strappingposition, guide means for guiding a strap through a loop within theconfines of which the article rests when in strapping position, grippingmeans for holding the leading end of the strap in spaced overlappingrelationship with respect to another portion of the strap, a strapfeeding and tensioning wheel mounted adjacent said support for rotationabout a horizontal axis, first and second guide rollers for directingthe strap about the major portion of the periphery of said wheel, saidfirst guide roller being located on that side of the vertical axis ofsaid wheel toward said support and said second guide roller beinglocated on the other side of the vertical axis of said wheel, reversibledrive means for rotating said wheel in strap feeding direction to feedstrap through said guide means to said gripping means and in tensioningdirection to tighten the strap about the article, means for moving saidfirst guide roller toward said wheel to pinch the strap therebetweenwhen said wheel is rotated in strap feeding direction and to move saidsecond guide roller toward said wheel to pinch the strap therebetweenwhen said wheel is rotated in strap tensioning direction, means forsecuring the overlapping portions of the strap together, and means forcutting the strap between the overlapping portions and said feeding andtensioning wheel.

13. Apparatus for securing a tensioned plastic strap about an article,said apparatus comprising a support for supporting an article instrapping position, guide means for guiding a strap through a loopwithin the confines of which the article rests when in strappingposition, gripping means for holding the leading end of the strap inspaced overlapping relationship with respect to another portion of thestrap, a strap feeding and tensioning wheel mounted adjacent saidsupport for rotation about a horizontal axis, first and second guiderollers for directing the strap about the major portion of the peripheryof said wheel, said first guide roller being located on that side of thevertical axis of said wheel toward said support and said second guideroller being located on the other side of the vertical axis of saidwheel, reversible drive means for rotating said wheel in strap feedingdirection to feed strap through said guide means to said gripping meansand in tensioning direction to tighten the strap about the article,means for moving said first guide roller toward said wheel to pinch thestrap therebetween when said wheel is rotated in strap feeding directionand to move said second guide roller toward said wheel to pinch thestrap therebetween when said wheel is rotated in strap tensioningdirection, a heating element, means for moving said heating element to aposition between the overlapping strap portions, squeezing means forsqueezing the overlapping strap portions against said heating element,means for withdrawing said heating element from between said overlappingstrap portions after the face areas of said strap portions have beensoftened, said squeezing means squeezing the softened face areas of thestrap together to produce a fused joint, and means for cutting the strapbetween the fused joint and said strap feeding and tensioning wheel.

14. Strap feeding and tensioning mechanism comprising a wheel mountedfor rotation on a horizontal axis, first and second rollers mounted nearhorizontally adjacent quadrants of said wheel whereby a strap may betrained about said rollers and a major portion of the periphery of saidwheel, means for rotating said wheel in strap feeding direction to movethe strap toward said first roller and in strap tensioning direction tomove the strap toward said second roller, means for moving said firstroller toward the periphery of said wheel to pinch the strapthereagainst when said wheel is rotated in strap feeding direction andmeans for moving said second roller toward the periphery of said wheelto pinch the strap thereagainst when said wheel is rotated in straptensioning direction.

15. In an automatic strapping machine, a strapping station, a strapfeeding wheel mounted for rotation on a horizontal axis and about amajor portion of the periphery of which strap from a supply is directed,means for rotating said wheel in forward direction to feed the straptoward the strapping station and in reverse direction to withdraw strapfrom the strapping station and tension the same about an object locatedat the strapping station, a first strap guiding roller located adjacentthe periphery of said wheel on that side of the horizontal axis of thewheel toward the strapping station, means for moving said roller towardthe periphery of the wheel to force the strap against said wheel whensaid wheel is rotated in forward direction, a second strap guidingroller located adjacent the periphery of the wheel on that side of thehorizontal axis of the wheel away from the strapping station and meansfor moving said second roller toward the periphery of the wheel to forcethe strap against the wheel when said wheel is rotated in reversedirection.

References Cited The following reference, cited by the Examiner, are ofrecord in the patented file of this patent or the original patent.

12 UNITED STATES PATENTS 4/1956 Allison 53-198 12/1961 Fryer 100-31 X R5/4962 Fryklund 100-14 4/1963 Van der Wal 100-33 X R 1/1964- Rollo eta1. 100-33 X R 9/1964 Van de Bilt 100-4 6/1965 Gelling et a1. 156-510 XR 11/1927 McChesney 100-2 9/1940 Harvey et a1. 100-4 9/1945 Cutter156-366 1/ 1956 Cheesman 100-27 4/1959 Winkler et a1. 100-25 8/1965Chisholm 156-499 5/ 1967 Bartlett 53-33 FOREIGN PATENTS 6/1963 France100-26 1/1940 Great Britain 100--30 12/1958 Great Britain 100-30 US. Cl.X.R.

